Chess Article #53:
The Chess endgame: The Cochrane Defense
Adapted and Condensed from
Wikipedia, the Free Encyclopedia
The Cochrane Defense is a method for drawing in the chess endgame
with a rook versus a rook and bishop. It was discovered by John
Cochrane. This combination of material is one of the most common
pawnless chess endgames. Many of the longest chess games on record
have this combination of material since at one time the fifty-move
rule which would make the game a draw after fifty moves with no
capture was extended to one-hundred moves for this combination of
material. For example, the longest tournament game on record is a
269-move game by Ivan Nikolic and International Master Goran
Arsovic. The last 103 moves of this game had this material and
ended in a draw.
Accurate play is required for the defense. The defense is most
effective near the center of the board, and doesn't work on the
edge (Nunn 2007:174ff). The Cochrane Defense works when:
* the defending rook pins the bishop to the king on one of the
four central files (c through f) or ranks (3 through 6), and
* there are two or more ranks or files (respectively) between
the kings (de la Villa 2008:213-16).
Details
Diagram #1:
White: King at e5, Rook at a7, Bishop at e4
Black: King at e8, Rook at e2
Budnikov-Novik, 1991
Cochrane defense. Black to move, draw with either side to move.
The defense is most effective near the center of the board. In this
position, if the pieces on the e-file were moved to the f-file,
then if 1. Ke5 the response 1. ... Kg8, puts the black king
dangerously close to the corner (Nunn 2007:161ff). The defense does
not work on the edge of the board.
In this position (Diagram #1) from a 1991 game between Alexandar
Budnikov and Maxim Novik, White would like to get his king to d6
and bishop to d5, to win by a method of Philidor (see Philidor
position; Rook and bishop versus rook, Chess Article #52#) -
however the pin of the bishop to the king prevents it. If White
plays 1. Kd5 or 1. Kf5 then Black moves his king in the opposite
direction, so if the bishop then moves, the black rook cuts off the
white king. There is another drawing method in positions with this
set of material, called the "second rank" defense (with the king
and rook both on a rank or file next to the edge of the board).
However, the Cochrane Defense is more popular among grandmasters
(Nunn 2002:174ff).
There are some key ideas for the defender to observe:
* wait by moving the rook between e1 and e2
* answer Kd5 with ... Kf8 and Kf5 by ... Kd8
* drive the rook away from the seventh rank at the first
opportunity
* move the king away from the eighth rank, as near the center of
the board as possible
* once the king has left the back rank, hold off the attacking
king for a few moves
* when the white king gets back to the fifth rank (or equivalent
in other directions), switch the rook around and head for the
Cochrane position again (perhaps rotated 90 or 180 degrees).
This phase is important because the opposing king must not be
allowed to reach the sixth rank (or equivalent).
The game continued:
1. ... Re1
2. Kd5 Kf8!
3. Bf5 Re7!
4. Ra8+ Kf7
5. Ra1 Kf6
6. Bc8 Re5+
7. Kd6 Re2
8. Rf1+ Kg5
9. Bb7 Re3
10. Kd5 Re2
11. Kd4 Re7
12. Bd5 Re8
13. Rf7 Rb8
14. Ke5 Rb5
and the position is back to the basic Cochrane position, rotated 90
degrees, and the fifty-move rule is closer to coming into effect.
The Budnikov-Novik game continued, with the Cochrane position being
reached again. Eventually a draw was claimed by the fifty-move rule
(Howell 1997:145-47).